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WasteWater Operator License 2021 > Chemistry & Treatment - Q&A > Flashcards

Chemistry & Treatment - Q&A Flashcards

1
Q

Wastewater effluent is dechlorinated with:

a) sodium thiosulfate
b) sodium hypochlorite
c) sodium permanganate

A

a) sodium thiosulfate = bisulfite

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2
Q

Chlorine that remains after consumed by organics in the water is called:

a) Residual chlorine
b) Total chlorine
c) Partial chlorine

A

a) Residual chlorine

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3
Q

For effective chlorine disinfection, the pH should be

a) Greater than 8
b) Less than 8
c) Greater than 9
d) Less than 6.5

A

b) Less than 8

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4
Q

When water is >pH 8.0 for effective disinfection what must one do?

a) Reduce chlorine concentration
b) Reduce contact time
c) Reduce both chlorine concentration and contact time
d) Increase chlorine concentration or contact time

A

d) Increase chlorine concentration or contact time

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5
Q

____ measures the organic strength of wastewater

a) pH
b) BOD
c) Total Dissolved Solids
d) Oil & Grease

A

b) BOD

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6
Q

____ test typically takes 2 hours to complete

a) Chlorine residual
b) Oxidation Reduction Potential (ORP)
c) pH
d) COD

A

d) COD

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7
Q

How much contact time is needed for effective disinfection at a chlorine residual of greater than 0.5mg/L?

a) half hour
b) one hour
c) two hours
d) three hours

A

a) half hour

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8
Q

A grab sample is one collected over a long period of time

a) true
b) false

A

b) false

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9
Q

A ______ is a single, identifiable source of pollution, such as a pipe or a drain

a) non-point source
b) BOD
c) point source
d) pH

A

c) point source

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10
Q

In wastewater treatment, the term BOD stands fro

a) biological oxygen demand
b) bench organic dose
c) biochemical oxygen demand
d) best oxidation details

A

c) biochemical oxygen demand

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11
Q

pH is measured in:

a) millivolts
b) standard units
c) mg/L
d) watts

A

b) standard units

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12
Q

Turbidity does not affect disinfection:

a) true
b) false

A

b) false

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13
Q

POE stands for

a) point of effectiveness
b) point of entry
c) point of end
d) point of essence

A

b) point of entry

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14
Q

Which of the following best describes adsorption?

a) Converting small particles of suspended solids into larger particles by the use of chemicals
b) assimilation of one substance into the body of another by molecular and chemical action
c) Chemical complexing of metallic cations with certain inorganic compounds
d) Adhesion of a gas, liquid or dissolved substance onto the surface or interface zone of another substance

A

d) Adhesion of a gas, liquid or dissolved substance onto the surface or interface zone of another substance

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15
Q

Chlorine gas is ____ times heavier than air

a) 3.0
b) 1.5
c) 2.5
d) 2.0

A

c) 2.5

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16
Q

Hydrogen sulfide will exist in a system depending on the presence or absence of

a) iron bacteria
b) organic acids
c) inorganic sulfides
d) oxygen

A

d) oxygen

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17
Q

An acceptable pH range for an industrial discharge is:

a) 0-14
b) 2-10
c) 5-7
d) 6-9

A

d) 6-9

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18
Q

Which of the following is a correct set of characteristic of chlorine as used in pollution control?

a) Chlorine gas is colorless, flammable and heavier than air
b) Chlorine gas is colorless, flammable and lighter than air
c) Chlorine gas is greenish-yellow (amber) in color, lighter than air, and insoluble in water
d) Chlorine gas is greenish-yellow (amber) in color, toxic, lighter than air, and non-corrosive
e) Chlorine gas is toxic, corrosive and heavier than air

A

e) Chlorine gas is toxic, corrosive and heavier than air

19
Q

Composite sample can be used for determining

a) pH
b) oil and grease
c) BOD/CBOD
d) Fecal coliform

A

c) BOD/CBOD

20
Q

Chlorine may be applied for hydrogen sulfide control in the ___?

a) aeration tank
b) collection lines
c) plant effluent
d) trickling filter
e) final effluent

A

b) collection lines

21
Q

A chlorine leak can be detected by ____

a) checking the leak gauge or vacuum
b) an explosimeter
c) spraying ammonia solution on the suspected leak
d) grain deposits on meta
e) none of the above

A

c) spraying ammonia solution on the suspected leak

white cloud

22
Q

Which of these chemicals are used for coagulation?

a) quaternary ammonia compounds
b) ferric chloride and alum
c) nutrients
d) all of the above

A

b) ferry chloride and alum

23
Q

A BOD sample is transported to the laboratory for analysis in a?

a) beaker
b) bucket
c) stainless steel jar
d) polyethylene or glass bottle

A

d) polyethylene or glass bottle

24
Q

TOC stands for:

a) The Organic Contaminant
b) Theoretical Organics Compounds
c) Total Organic Carbon
d) Total Organism Count

A

c) Total Organic Carbon

25
Q

Pathogenic bacteria are

a) inorganic
b) easy to see
c) disease causing
d) none of these

A

c) disease causing

26
Q

Toxic pollutants are identified by EPA as compounds or classes that are:

a) capable of causing illness in humans
b) difficult to treat by conventional water treatment processes
c) harmful to one or more forms of plan or animal life
d) known to cause acute illness

A

c) harmful to one or more forms of plan or animal life

27
Q

What tests are used to measure the strength of wastewater

a) pH & BOD
b) SS & pH
c) pH & DO
d) DO & BOD
e) BOD & SS

A

e) BOD & SS

28
Q

The theoretical nutrient requirements in activated sludge treatment system, commonly referred to as the BOD:N:P (BOD:Nitrogen:Phosphorus) ratio should be:

a) 100:5:1
b) 20:5:1
c) 1000:2:1
d) 10:3:1

A

a) 100:5:1

29
Q

What do the “bugs” need to stay healthy?

a) DO and food or BOD
b) nutrients
c) proper F/M and sludge age
d) all of the above

A

d) all of the above

30
Q

Is activated sludge suspended or fixed growth?

a) fixed growth
b) suspended growth

A

b) suspended growth

31
Q

Which of these chemicals are used primarily for lowering pH of wastewater?

a) NaOH
b) Ferric Chloride
c) Sulfuric Acid
d) Lime

A

Find answer

32
Q

Young sludge is indicated by which of the following visual appearance:

a) dark brown foam
b) white foam
c) yellow foam
d) dark clouds

A

b) white foam

33
Q

What is one of the golden rules of keeping microbes healthy in the activated sludge process?

a) add enough oxygen for the bugs to thrive and mix tank contents
b) keep them out of sunlight
c) don’t give them any water
d) never feed them after midnight :)

A

a) add enough oxygen for the bugs to thrive and mix tank contents

34
Q

Chlorine is the most effective against which of the following?

a) protozoa
b) viruses
c) bacteria
d) hardness

A

c) bacteria

Not effective against protozoa

35
Q

The holding fo a BOD sample is

a) 14 days
b) 28 days
c) 7 days
d) 48 hrs

A

d) 48 hrs

The holding time for a BOD sample is 48 hours from collection. The test itself requires a five day incubation period.

36
Q

Sodium hypochlorite is usually at what strength for water and wastewater disinfection?

a) 10-15%
b) 5-10%
c) 1-5%
d) 50%

A

a) 10-15%

37
Q

Chlorine kills all harmful microorganisms

a) True
b) False

A

b) False

38
Q

In wastewater, the most common form of disinfection is:

a) ozone
b) UV
c) chlorine

A

c) chlorine

39
Q

Protozoa are:

a) bacteria
b) viruses
c) giardia / cryptosporidium

A

c) giardia / cryptosporidium

40
Q

When chlorine is added to the water, what is formed?

a) chlorine residual
b) hypochlorus acid
c) pH

A

b) hypochlorus acid

Hypochlorus acid is the part that does the “kill” / the disinfection

41
Q

Chlorine disinfection efficiency when:

a) Water temperatures are colder and pH is higher
b) Water temperatures are higher and pH is lower

A

b) Water temperatures are higher and pH is lower

42
Q

When chlorine is added to the water which disinfectant is strongest?

a) hypochlorus acid
b) hypochlorite ion
c) hydrogen chloride

A

a) hypochlorus acid

43
Q

For neutralization, is it better to have low or high pH?

A

Neutralization is important part of corrosion control.

The lower the pH, the greater rate of corrosion.

WasteWater Operator License 2021 (10 decks)

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